Low-temperature vacuum heat insulation structure for liquid helium Dewar tank

Abstract

The utility model relates to a low-temperature vacuum heat insulation structure for a liquid helium Dewar tank, which belongs to the technical field of heat insulation and comprises an inner container consisting of a lower seal head at the bottom, a barrel in the middle and an upper seal head at the top, a neck tube is arranged at the upper seal head, a plurality of fins are arranged on the neck tube, and the fins are arranged in the inner container. The outer side of the inner container is alternately wrapped with a plurality of heat insulation blocking units and flexible anti-radiation cold shield units from inside to outside, the number of the heat insulation blocking units is one more than that of the flexible anti-radiation cold shield units, and the number of the flexible anti-radiation cold shield units is consistent with that of the fins. And the flexible anti-radiation cold shield units are in one-to-one correspondence with the fins and cover the outer sides of the corresponding fins. The flexible anti-radiation cold shield unit is used as a heat conduction gap bridge between the fins and the cylinder body, the temperature of the middle part of the heat insulation material is reduced through the gas-phase cooling capacity at the neck pipe, and the heat insulation effect is good.

Description

Technical Field

[0001] The utility model relates to the insulation technology field of vacuum insulation cryogenic pressure vessels, in particular to a low-temperature vacuum insulation structure for a liquid helium Dewar tank body. Background Art

[0002] The liquid helium dewar is a container for holding a liquid helium medium at a temperature of 4.5K. The liquid helium dewar is an inner and outer sandwich container structure, with a high vacuum sandwich in the middle, and the inner container is wrapped with insulation material. The above structures are all for improving the insulation performance of the dewar. The existing liquid helium dewar, such as the liquid helium dewar disclosed in the Chinese patent with the authorization announcement number CN218348407U, includes an outer shell, an inner liner, a neck tube, a reflective component and an insulation component. The inner liner is arranged in the outer shell, and the reflective component includes a first reflector and a second reflector. The first reflector and the second reflector are The injection piece is sleeved on the neck tube at intervals along the axial direction of the neck tube; the insulation component includes a first insulation layer group, a second insulation layer group and a third insulation layer group, one end of the first insulation layer group is fixed on the inner liner and the first insulation layer group is longitudinally spirally wound on the inner liner, one end of the second insulation layer group is fixed on the first insulation layer group and the second insulation layer group is longitudinally spirally wound on the first insulation layer group and the first reflection piece, and one end of the third insulation layer group is fixed on the second insulation layer group and the third insulation layer group is longitudinally spirally wound on the second insulation layer group and the second reflection piece.

[0003] The gas phase temperature at the neck of the liquid helium Dewar is relatively low, and the existing technology does not utilize the cold energy of the gas phase, resulting in a waste of cold energy, making it impossible to further improve the thermal insulation performance of the insulation structure. Utility Model Content

[0004] The utility model aims to provide a low-temperature vacuum insulation structure for a liquid helium dewar tank, so as to solve the problem that the thermal insulation performance in the existing insulation structure cannot be further improved.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] The invention relates to a low-temperature vacuum insulation structure for a liquid helium dewar tank, comprising an inner liner composed of a lower head at the bottom, a cylinder in the middle and an upper head at the top, wherein a neck tube is provided at the upper head, a plurality of fins are provided on the neck tube, and the outer side of the inner liner is alternately wrapped with a plurality of heat insulation barrier units and flexible radiation-proof cold shield units from the inside to the outside, wherein the number of the heat insulation barrier units is one more than the number of the flexible radiation-proof cold shield units, the number of the flexible radiation-proof cold shield units is consistent with the number of fins, and the flexible radiation-proof cold shield units correspond to the fins one by one, and the flexible radiation-proof cold shield units cover the outer sides of the corresponding fins.

[0007] Preferably, the thermal insulation barrier units all include a plurality of reflective materials and spacer materials that are alternately stacked, and the total number of layers of reflective materials and spacer materials in all the thermal insulation barrier units is not less than 150 layers.

[0008] Preferably, the spacer material is polyester fiber paper or plant fiber paper with a gram weight of 10 to 14 g / m2 and a thickness of less than 0.06 mm.

[0009] Preferably, the reflective material is a vacuum aluminum-plated film material with a thickness of 0.01 to 0.015 mm.

[0010] Preferably, the surface of the reflective material is provided with circular holes to increase the air permeability of the overall structure and improve the vacuuming efficiency.

[0011] Preferably, the flexible radiation-proof cold shield unit is 2 to 3 layers of metal aluminum foil material or metal copper foil material.

[0012] Preferably, the thickness of the flexible radiation-proof cold shield unit is 0.018-0.025 mm.

[0013] Preferably, the exposed neck tube is wrapped with an outermost thermal insulation barrier unit.

[0014] Compared with the prior art, the technical solution provided by the utility model has the following technical effects:

[0015] 2. The low-temperature vacuum insulation structure for the liquid helium Dewar tank involved in the utility model is provided with fins at the neck tube. During the manufacturing process, the flexible radiation-proof cold shield unit covers the outer side of the corresponding fin, and the flexible radiation-proof cold shield unit is used as a heat conduction bridge between the fin and the cylinder. The gas phase cold at the neck tube is used to reduce the temperature of the middle part of the insulation material, so as to meet the insulation requirements and have better thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of a cryogenic vacuum insulation structure for a liquid helium dewar tank;

[0017] Figure 2 The present invention is a flow chart of a method for manufacturing a cryogenic vacuum insulation structure for a liquid helium dewar tank.

[0018] Among them: 1-inner liner, 2-first fin, 3-second fin, 4-third fin, 5-first insulation barrier unit, 6-first flexible radiation protection cold shield unit, 7-second insulation barrier unit, 8-second flexible radiation protection cold shield unit, 9-third insulation barrier unit, 10-third flexible radiation protection cold shield unit, 11-fourth insulation barrier unit, 12-neck tube. DETAILED DESCRIPTION

[0019] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0020] See attached Figure 1 As shown, the utility model relates to a low-temperature vacuum insulation structure for a liquid helium Dewar tank, comprising an inner tank 1 consisting of a lower head at the bottom, a cylinder in the middle and an upper head at the top, a neck tube 12 is provided at the upper head, and three fins are provided on the neck tube 12, which are respectively a first fin 2, a second fin 3 and a third fin 4 from the inside to the outside, and the outer side of the inner tank 1 is alternately wrapped with a plurality of thermal insulation barrier units and flexible radiation-proof cold shield units from the inside to the outside, and the thermal insulation barrier unit has one more unit than the flexible radiation-proof cold shield unit. In this embodiment, four thermal insulation barrier units are provided, and three flexible radiation-proof cold shield units are provided, which sequentially wrap a first thermal insulation barrier unit 5, a first flexible radiation-proof cold shield unit 6, a second thermal insulation barrier unit 7, a second flexible radiation-proof cold shield unit 8, a third thermal insulation barrier unit 9, a third flexible radiation-proof cold shield unit 10 and a fourth thermal insulation barrier unit 11 from the inside to the outside.

[0021] The thermal insulation barrier unit is prefabricated by staggered overlapping of n layers of reflective material and n layers of spacer material, n is an integer greater than or equal to 2, and the total number of layers of reflective material and spacer material in all thermal insulation barriers is not less than 150 layers. The fins correspond to the flexible radiation-proof cold shield units one by one, and the flexible radiation-proof cold shield units cover the outside of the corresponding fins. The spacer material is polyester fiber paper or plant fiber paper, with a gram weight of 10 to 14 g / m 2 , thickness is less than 0.06mm, the reflective material is vacuum aluminum-plated film material with a thickness of 0.01-0.015mm, and circular holes are opened on the surface of the reflective material. The circular holes are φ4 holes and are arranged in a matrix of 100*200mm.

[0022] The flexible radiation-proof cold shield unit is made of metal aluminum foil material or metal copper foil material. Each flexible radiation-proof cold shield unit is configured with two layers of metal aluminum foil material or two layers of metal copper foil material with a thickness of 0.018 to 0.025 mm.

[0023] In this embodiment, the first heat-insulating barrier unit 5 is made of vacuum aluminum-plated film material and polyester fiber paper alternately laid in 10 layers, with the polyester fiber paper at the bottom and the vacuum aluminum-plated film material at the top, and is prefabricated by a laser cutting machine. The surface of the vacuum aluminum-plated film material is punched with φ4 holes, with an interval of 100*200mm; the second heat-insulating barrier unit 7 is made of vacuum aluminum-plated film material and polyester fiber paper alternately laid in 15 layers, with the polyester fiber paper at the bottom and the vacuum aluminum-plated film material at the top, and is prefabricated by a laser cutting machine. The surface of the vacuum aluminum-plated film material is punched with φ4 holes, with an interval of 100*200mm. mm; the third thermal insulation barrier unit 9 is made of vacuum aluminized film material and polyester fiber paper alternately laid in 25 layers, with the polyester fiber paper at the bottom and the vacuum aluminized film material at the top, and is preformed by a laser cutting machine. φ4 holes are punched on the surface of the vacuum aluminized film material, with an interval of 100*200mm; the fourth thermal insulation barrier unit 11 is made of vacuum aluminized film material and polyester fiber paper alternately laid in 35 layers, with the polyester fiber paper at the bottom and the vacuum aluminized film material at the top, and is preformed by a laser cutting machine. φ4 holes are punched on the surface of the vacuum aluminized film material, with an interval of 100*200mm.

[0024] In this embodiment, the first flexible radiation-proof cold shield unit 6 includes 2 layers of the first flexible radiation-proof cold shield layer, the second flexible radiation-proof cold shield unit 8 includes 2 layers of the second flexible radiation-proof cold shield layer, and the third flexible radiation-proof cold shield unit 10 includes 3 layers of the second flexible radiation-proof cold shield layer. When laying a certain flexible radiation-proof cold shield unit, each flexible radiation-proof cold shield layer is laid in sequence. The first flexible radiation-proof cold shield layer, the second flexible radiation-proof cold shield layer, and the third flexible radiation-proof cold shield layer are all made of 0.025 mm thick aluminum foil material, and the surface is not perforated. A first fin 2 is arranged between the first thermal insulation barrier unit 5 and the first flexible radiation-proof cold shield unit 6 at the neck tube 12, a second fin 3 is arranged between the second thermal insulation barrier unit 7 and the second flexible radiation-proof cold shield unit 8 at the neck tube 12, and a second fin 4 is arranged between the third thermal insulation barrier unit 9 and the third flexible radiation-proof cold shield unit 10 at the neck tube 12.

[0025] See attached Figure 2 As shown, the manufacturing method of the cryogenic vacuum insulation structure for the liquid helium Dewar tank comprises the following steps:

[0026] S1. Alternately lay the designed number of layers of spacer materials and reflective materials, and prefabricate the heat insulation barrier unit by sewing with absorbent cotton thread or laser cutting composite molding according to the size of the liner;

[0027] S2. Wrap the outer side of the inner liner 1 with an insulating barrier unit, and the order of wrapping the insulating barrier unit is: first wrap the insulating barrier unit at the lower head of the inner liner, then wrap the insulating barrier unit at the inner liner cylinder, and finally wrap the insulating barrier unit at the upper head of the inner liner, thereby forming a first insulating barrier unit 5.

[0028] S3. A flexible radiation-proof cold shield unit is wrapped on the outside of the thermal insulation barrier unit, and the flexible radiation-proof cold shield unit covers the fins of the corresponding layer. The order of wrapping the flexible radiation-proof cold shield unit is: first wrap the flexible radiation-proof cold shield unit at the lower head of the inner liner, then wrap the flexible radiation-proof cold shield unit at the inner liner cylinder, and finally wrap the flexible radiation-proof cold shield unit at the upper head of the inner liner. When wrapping the flexible radiation-proof cold shield unit at the upper head, the flexible radiation-proof cold shield unit covers the fins of the corresponding layer; thereby forming a first flexible radiation-proof cold shield unit 6.

[0029] S4. Determine whether all fins are covered. If not, return to S2 and complete the second insulation barrier unit 7, the second radiation protection cold shield unit 8, the third insulation barrier unit 9, and the third radiation protection cold shield unit 10 in sequence; if so, wrap a layer of insulation barrier unit (fourth insulation barrier unit 11) outside the outermost flexible radiation protection cold shield unit (third radiation protection cold shield unit 10) in accordance with step 2.

[0030] S5. Use a glass fiber tape to tie up the outermost insulating barrier unit or a nylon net to cover the entire insulating barrier unit, and use the insulating barrier unit to cover the exposed neck tube 12 to complete the covering.

[0031] For the liquid helium dewar tank covered with insulation structure, the test process is as follows: prepare materials and construct as above. After the inner and outer tanks are fitted together, the interlayer is evacuated, and after the inner tank is filled with liquid helium, the cold vacuum degree is less than 5*10 -3 Pa, connected to the mass flow meter, and carried out a static evaporation rate test according to GB / T 18443.5 "Vacuum Insulation Cryogenic Equipment Performance Test Method Part 5: Static Evaporation Rate Measurement". The static evaporation rate of the overall structure was calculated to be 1.25%. This result is similar to the winding process construction, and both meet the static evaporation rate requirements of relevant units for liquid helium Dewar tanks.

[0032] The above is a detailed description of the utility model in combination with the embodiments, but the contents described are only preferred embodiments of the utility model and cannot be considered to limit the scope of implementation of the utility model. All equivalent changes and improvements made within the scope of application of the utility model should still fall within the scope of the patent coverage of the utility model.

Claims

1. A low-temperature vacuum insulation structure for a liquid helium dewar tank, comprising an inner liner consisting of a lower head at the bottom, a cylinder in the middle and an upper head at the top, wherein a neck tube is provided at the upper head, and the characteristics are: A plurality of fins are arranged on the neck tube, and the outer side of the inner tank is alternately wrapped with a plurality of thermal insulation barrier units and flexible radiation proof cold shield units from the inside to the outside, the number of the thermal insulation barrier units is one more than the number of the flexible radiation proof cold shield units, the number of the flexible radiation proof cold shield units is consistent with the number of fins, and the flexible radiation proof cold shield units correspond to the fins one by one, and the flexible radiation proof cold shield units cover the outer sides of the corresponding fins.

2. The low-temperature vacuum insulation structure for a liquid helium dewar tank according to claim 1, characterized in that: The heat-insulating barrier units all include a plurality of reflective materials and spacer materials that are alternately stacked, and the total number of layers of reflective materials and spacer materials in all the heat-insulating barrier units is not less than 150 layers.

3. The low temperature vacuum insulation structure for a liquid helium dewar tank according to claim 2, characterized in that: The spacer material is polyester fiber paper or plant fiber paper, with a gram weight of 10-14g / m 2 , thickness is less than 0.06mm.

4. The low temperature vacuum insulation structure for a liquid helium Dewar tank according to claim 2, characterized in that: The reflective material is a vacuum aluminum-plated film material with a thickness of 0.01 to 0.015 mm.

5. The low-temperature vacuum insulation structure for a liquid helium Dewar tank according to claim 4, characterized in that: The surface of the reflective material is provided with round holes.

6. The low temperature vacuum insulation structure for a liquid helium dewar tank according to claim 1, characterized in that: The flexible radiation-proof cold shield unit is made of 2 to 3 layers of metal aluminum foil material or metal copper foil material.

7. The low temperature vacuum insulation structure for a liquid helium dewar tank according to claim 1, characterized in that: The thickness of the flexible radiation-proof cold shield unit is 0.018-0.025 mm.

8. The low temperature vacuum insulation structure for a liquid helium dewar tank according to claim 1, characterized in that: The exposed neck tube is wrapped with an outermost thermal insulation barrier unit.

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